1. Field of the Invention
The present invention relates generally to powered machines adapted for refinishing floors and similar surfaces. More particularly, the present invention comprises an automated, self propelled drum-type floor sander or refinisher incorporating a variable speed drive, a mechanism for raising and lowering the drum by control of the operator or automatically according to the speed of the machine, and a novel sanding belt centering mechanism. The above features may be incorporated singly or in combination in a floor sanding or refinishing machine, as desired. While the various embodiments of the present invention are directed primarily to a drum type powered sanding machine for use on floors, it will be seen that it is not limited to such use, but may be incorporated in various types of walk behind or ride behind floor or surface refinishing and treatment mechanisms, as desired.
2. Description of the Related Art
A large number of powered floor sanders and polishers have been developed over the years, in order to facilitate such work. These powered devices universally include either a drum or a disc powered by an electric motor or other prime mover, and some form of controls for an operator of the machine. Many such devices are sufficiently large as to provide seating for the operator, either integrally with the sanding or refinishing mechanism or as ride behind mechanism with controls.
One problem with such powered devices is that they are prone to damaging the floor if the movement of the machine is not maintained uniformly and consistently over the surface. If the machine progresses too slowly, the sanding drum or disc will remove too much material in that area, resulting in a low spot in the floor. Various mechanisms have been developed to allow the operator to lift the drum, or at least to reduce its pressure on the underlying surface, but the operator must be sufficiently skilled so as to control the machine precisely to avoid gouging the floor with such manually controlled mechanisms.
Another problem with conventional machines is the lack of speed control for the machine. While many powered machines are known which provide propulsion of the machine in addition to power for the sanding drum, such machines generally do not facilitate ready control of the machine's travel speed over the surface, and may have only a single forward speed, a single reverse speed, and/or a neutral or off configuration. This can lead to the same problem noted above, i.e. excessive sanding of the surface in one spot or area due to the machine being stopped or traveling too slowly, or conversely, too rapid a speed over an area which requires additional work.
Yet another problem with conventional machines is the difficulty in keeping the sanding belt centered upon the drum. While various mechanisms are known, they generally rely upon auxiliary rollers near the opposite ends of an idler roller, but misalignment of the belt will often overpower this system.
Thus, an automated floor sander solving the aforementioned problems is desired.